JD 3320 will not move after calibrating throttle sensor

[Nosille]

I recently purchased a JD3320. It was showing a few error codes when I bought it but operated fine, so I talked the guy down a little and brought the tractor home. Upon getting it home, I started tracking down the codes. For code 08 the users manual said to check the throttle sensor, and upon inspection I found that the sensor bracket was bent and no longer engaging the throttle. A little finessing with a hammer got it back in place, and a little time with a voltage gage got the idle readings back where it should be, ~0.790 volts. While searching this site for the proper voltage, I ran across a calibration procedure that I decided to try as well. Everything seemed to have gone well. Tractor cranked right up with no error codes. However, when I went to get it out of the shop the hydro would not engage. I know it has to have something to do with the calibration, but I have repeated it multiple times on the throttle and both hydro pedals with no success. Any ideas?

 

[sd455dan]

Well IF that is a basic Throttle position sensor , most vehicles computers send a regulated +5 volts to the TPS which is a variable resistor.
When you hammered the mount into place it may have damaged part of the resistor which sends back a portion of the voltage depending on the throttles position .
I would ground one side of a volt meter and then check that with a key on
that the return wire from the sensor is varying from the .7volt or so at idle position thru about 4.5 to 5 volts wide open... obviously the engine is not running during testing.

Is there a neutral position and if so does the throttle (engine speed respond normally)?

If this is not a TPS then what i posted is probably useless

 

[Cocre]

Turn off LoadMatch, see if that helps. I had issues once with LoadMatch (no errors) and re-calibrating the TPS resolved the issue. It seemed to be the only symptom of an out-of-range TPS. If the TPS is way bad perhaps Loadmatch would keep the tractor from moving at all.

 

[Nosille]

Well IF that is a basic Throttle position sensor , most vehicles computers send a regulated +5 volts to the TPS which is a variable resistor.
When you hammered the mount into place it may have damaged part of the resistor which sends back a portion of the voltage depending on the throttles position .
I would ground one side of a volt meter and then check that with a key on
that the return wire from the sensor is varying from the .7volt or so at idle position thru about 4.5 to 5 volts wide open... obviously the engine is not running during testing.

Is there a neutral position and if so does the throttle (engine speed respond normally)?

If this is not a TPS then what i posted is probably useless

I hammered out the bracket after removing the sensor. The sensor reads ~0.790 volts at min throttle and around ~2.9 at full throttle. Engine revs fine.

 

[Nosille]

My service manual arrived today, and after studying it, I decided to go through a full hydro calibration. After some initial difficulties with the petals reading high at full travel, I managed to get most of the way through the calibration. However, I keep getting an error during the forward coil calibration.

The calibration always proceeds like it is going to work. The tires start slowly, but gradually pick up speed. They work their way up to a pretty good speed, but then stop suddenly with a flashing error message. Has anyone else experienced this problem? Any trouble shooting suggestions? Would the MFWD speed sensor be a factor? I am prettying sure my MFWD sensor is out.

I assume I am stuck needing to complete a full calibration now. I really need to get the tractor usable again. I can't believe what started as a simple attempt to fix a bent bracket has devolved into an unusable tractor.

 

[Coyote machine]

Starting at your beginning point, the tractor was able to run and move BEFORE you touched the bent bracket, yes?
Did the bracket look like it might have been bent on purpose? If so it would seem logical the prior owner knew something was wrong, and might have disabled the sensor by bending the bracket?
You said there were a bunch of error codes present when you bought it, right?
What if you were to disable the TPS again just to see what happens?
You can fix it later if you can get to use it now, right? It may be beyond a calibration, and need further troubleshooting of codes before you can actually fix it to specs.

I'm not familiar with the MFWD, and something you said was 'out', do you mean out of spec/range/calibration?
Forward coil too, needing adjustment?

My sense of it is you've adjusted a lot of items and going back to square 1 may be your best approach at this juncture; after all, unless someone already did all you're doing and messed it all up it wouldn't likely have run and moved for you originally....

 

[arlen4720]

what are the specific error codes?

 

[Nosille]

Yes the tractor would drive before I touched the bent bracket. I have thought the same thing about the bracket being bent on purpose, and I did try bending it back for a short while after this whole thing started. However, at this point I cannot see how a bent bracket will help me. All that would do is make the computer think the tractor is always at idle. I assume some previous mechanic could have gone through a process where he moved the sensor by hand at critical points in the calibration process to get a desired result, but I do not know what it would be.

I would love to go back to square one, but now that the computer has tried to calibration, I do not think it is possible.

 

[Nosille]

what are the specific error codes?

The original error codes were 06 and 08. However, I do not have any standing error messages right now. The first time I turn the key on after a failed calibration, it flashes 04 and 06 once and then clears.

 

[arlen4720]

The original error codes were 06 and 08. However, I do not have any standing error messages right now. The first time I turn the key on after a failed calibration, it flashes 04 and 06 once and then clears.

So 4, 6, and 8. Engine speed, MFWD Speed, and Thottle position. I'm thinking the calibration failed becuase you tried to calibrate without a working MFWD speed sensor (ERR_06). The tractor will still work at a degraded level without the throtttle position and MFWD speed sensors, but maybe really went to pot when you tried to calibrate.
Your symptoms during calibration fits....It spins the wheels for a time, then, when it doesn't detect wheel movement, throws an error and aborts.
I think I would look over the wires to that sensor closely. Maybe replace it and try again.